Patent GB-682488-A (GB)
Title: Improvements in or relating to organosiloxane co-polymers
IPC: C08G77/06
Filed: 1950-11-22
Abstract: Copolymeric siloxanes are made by contacting in the liquid phase a compound of the general formula RO[(CH3)2SiO]nR, in which n is an integer from 1 to 11 inclusive and R is an alkyl radical containing less than 5 carbon atoms or a mixture of such compounds, with a silane diol of the general formula R12Si(OH)2, in which each R1 is a tertiary-butyl or phenyl radical, and removing by vaporization the alcohol produced.  The reaction may be executed at normal, sub- or super-atmospheric pressures and at a temperature of at least the boiling point of the by-produced alcohol at the pressure employed. Catalysts such as sulphuric or hydrochloric acid and sodium or potassium hydroxide may be used. In examples: (1) on heating di-t-butylsilanediol and dimethyldiethoxysilane with cone.  H2SO4 and distilling off ethanol and unreacted silane, a polysiloxane residue was obtained from which crystalline 1,1,5,5-tetramethyl 3,3,7,7-tetra-t-butylcyclotetrasiloxane and liquid dimethyl di-t-butylpolysiloxane were isolated; (2) reaction of t-butylphenylsilanediol and dimethyldiethoxysilane yielded dimethyl - t - butylphenylpolysiloxane as a viscous liquid; (3) reaction of diphenylsilanediol and dimethyldiethoxysilane yielded crystalline 1,1,5,5-tetramethyl-3,3,7,7-tetraphenylcyclotetrasiloxane and dimethyldiphenylpolysiloxane; (4) reaction of diphenylsilanediol with tetramethyl - 1,3 - diethoxydisiloxane, EtO(Me2SiO)2Et, yielded crystalline 1,1-diphenyltetramethylcyclotrisiloxane and a liquid ethoxy end-blocked dimethyldiphenylpolysiloxane; (5) reaction of dimethyldiethoxy silane hydrolysate, after removal of low boiling components, with diphenylsilanediol yielded liquid dimethyldiphenylpolysiloxane.  Besides cyclic polysiloxanes of the general formula [(CH3)2SiO]x[R12SiO]y, in whic x and y are integers totalling at least 3, linear hydroxy or alkoxy end-blocked copolymers are also formed.  The products may be used as damping fluids and in hydraulic pressure systems.  The crystalline cyclic copolymers may be further copolymerized, e.g. with octamethylcyclotetrasiloxane, to produce liquids useful as lubricants.  Specifications 618,459 and 657,442 are referred to.ALSO:Copolymeric siloxanes are made by contacting in liquid phase a compound of the general formula RO[(CH3)2SiO]nR, in which n is an integer from 1 to 11 inclusive and R is an alkyl radical containing less than 5 carbon atoms, or a mixture of such compounds, with a silane diol of the general formula R12Si(OH)2, in which each R1 is a tertiary butyl or phenyl radical, and removing by vaporization the alcohol produced.  The reaction may be executed at normal, sub- or super-atmospheric pressures and at a temperature of at least the boiling-point of the by-produced alcohol at the pressure employed. Catalysts such as sulphuric or hydrochloric acid, and sodium or potassium hydroxide may be used.  In examples: (1) on heating di-t.-butyl-silanediol and dimethyldiethoxysilane with concentrated sulphuric acid and distilling off ethanol and unreacted silane, a polysiloxane residue was obtained from which crystalline 1,1,5,5 - tetramethyl - 3,3,7,7 - tetra - t. - butylcyclotetrasiloxane was isolated; (3) reaction of diphenylsilanediol and dimethyldiethoxy silane yielded, inter alia, crystalline 1,1,5,5-tetramethyl - 3,3,7,7 - tetraphenylcyclotetrasiloxane; (4) reaction of diphenylsilanediol with tetramethyl - 1,3 - diethoxydisiloxane, EtO(Me2 SiO)2Et, yielded, inter alia, crystalline 1,1-diphenyltetramethylcyclotrisiloxane.  Besides cyclic polysiloxanes of the general formula [(CH3)2SiO]x[R12SiO]y, in which x and y are integers totalling at least 3, linear hydroxy or alkoxy end-blocked copolymers are also formed.  Specifications 618,459, [Group IV (a)], and 657,442 are referred to.